Case is created but auto-reply mail does not work properly

Hi,
Case is created automatically from Inbound mails but auto-reply mail for Case creation is not working properly as the variable name itself displayed instead of values. Kindly suggest me to solve this issue and display the variable name with values in Case creation mail sent on successful case creation.

Hi $contact_first_name $contact_last_name,

We’ve received your case $acase_name (# $acase_case_number) on $acase_date_entered

Status $acase_status
Reference $acase_case_number
Description $acase_description

(The above auto-reply mail is to replaced with values)

Thanks in advance.